Why is rape in itself not more of a wicked sin then homosexuality?
Because - violating the natural order that God set up is far worse, more wicked, more evil - in His eyes - than doing evil within that natural order. As bad, wrong, and evil a thing it is for a man to rape a woman - in God's eyes - it is far, far, far more wicked to 'violate' God Himself (please understand the context) by crossing a God-ordained boundary in His creation that God intended should never be crossed - not even once.
2 Peter 2:
4 For if God spared not the angels that sinned, but cast them down to hell, and delivered them into chains of darkness, to be reserved unto judgment;
Jude 1:
6 And the angels which kept not their first estate, but left their own habitation, he hath reserved in everlasting chains under darkness unto the judgment of the great day.
The angels referred to in these verses crossed a boundary God intended should never be crossed. They "messed with" God's creation in a way they were never supposed to.
God is greatly offended when angels or people "mess with" the natural order of His creation - doing things He intended should never happen - things that are a wicked abomination to Him.
You need to understand this. God is very serious about the way He set up His creation.
The natural order is "one man and one woman" -
anything else is the worse kind of wicked abomination that there is - because, it violates the natural order of the creation.
There are many things that are bad, wrong, sinful, evil, etc. - and, they are all sin against God. And, I am not suggesting anything otherwise. What I will suggest is that anything that violates the natural order of God's creation - in a way - violates God Himself.
I dare say that two "consenting adult males" violating the natural order of God's creation is "worse" - in God's eyes - than a man raping a woman.
It is still very bad, wrong, sinful, evil, etc. to rape a woman. And, I am not suggesting anything otherwise.
It is all bad, wrong, sinful, evil, etc. - nonetheless, you have to look at it from God's perspective.
God created 'masculine' and 'feminine' the way He did for very good reasons. (And Satan is doing everything he can to try to wreck it.)
Men are supposed to look, dress, act, etc. like men. Women are supposed to look, dress, act, etc. like women.
These things are very important to God. And, anything that violates the way He intends for it to be is an abomination to Him.